A blow moulding device of the abovementioned type is in particular described in the document FR 2 790 704.
It is common practice for the blanks or preforms to be heated beforehand in a thermal conditioning oven before being transferred into a mould of a blow moulding device using a transfer wheel having a plurality of gripping arms on a periphery thereof.
In order to place the body of the blank or preform in the moulds, the control for opening the gripping arms of the transfer wheel is synchronized with the control for opening and closing the moulds, the body of the heated blank being inserted into the open mould and released once the mould is closed, the blank or preform then resting, by means of a radially-projecting annular flange provided in the neck part of the preform, against the upper surface of the mould.
However, in order to reduce the production costs of the blow moulded containers, it is common practice to reduce the mass of the preforms.
Thus, due to the fact that the heated blank rests on the upper surface of the mould only by means of flange thereof, the forces of gravity are not always sufficient to adequately hold the flange against the upper surface of the mould, which results in preforms not placed substantially coaxially with the main axis of the blowing nozzle. This results in non-compliant blow moulded containers with flanges which are not in a transversal plane to the axis of the blowing nozzle, i.e. resulting in inclined flanges. These containers then have to be discarded for destruction.